Marine cable for offshore wind power having an improved water-tree property

Abstract

Disclosed is the present disclosure relates to a marine cable for offshore wind power having an improved water-tree property. More particularly, it relates to a marine cable for offshore wind power, which may effectively suppress formation of water trees caused by diffusion of moisture, having penetrated into cores of the cable, in insulating layers so as to improve dielectric strength and consequently secure a long lifespan.

What is claimed is: 
     
         1 . A marine cable for offshore wind power, comprising at least one core comprising a conductor and an insulating layer configured to surround the conductor,
 wherein sizes of water trees in the insulating layer, measured based on standard ASTM D6097, are equal to or less than 850 μm.   
     
     
         2 . The marine cable according to  claim 1 , wherein a degree of crosslinking of the insulating layer is equal to or greater than 77%, and a degree of crystallinity of the insulating layer is equal to or greater than 35%. 
     
     
         3 . The marine cable according to  claim 2 , wherein the insulating layer comprises crosslinked polyethylene (XLPE). 
     
     
         4 . The marine cable according to  claim 1 , wherein breakdown voltage (BDV) of the insulating layer is equal to or greater than 80 kV/mm. 
     
     
         5 . The marine cable according to  claim 1 , wherein the at least one core comprises the conductor, an inner semiconductive layer configured to surround the conductor, the insulating layer configured to surround the inner semiconductive layer, an outer semiconductive layer configured to surround the insulating layer, a wire shield layer configured to surround the outer semiconductive layer, and a core jacket configured to surround the wire shield layer. 
     
     
         6 . The marine cable according to  claim 5 , wherein the at least one core further comprises an inner water-barrier tape layer provided between the outer semiconductive layer and the wire shield layer and configured to surround the outer semiconductive layer, an outer water-barrier tape layer configured to surround the wire shield layer, and a metallic sheath layer configured to surround the outer water-barrier tape layer. 
     
     
         7 . The marine cable according to  claim 6 , wherein the outer water-barrier tape layer comprises at least one selected from the group consisting of powder, a tape, a coating layer, and a film, comprising a superabsorbent polymer (SAP). 
     
     
         8 . The marine cable according to  claims 1 , comprising a plurality of cores,
 wherein filling members are provided at a center among the plurality of cores and in regions outside the plurality of cores.   
     
     
         9 . The marine cable according to  claim 8 , wherein the filling members comprise yarns formed of polypropylene. 
     
     
         10 . The marine cable according to  claim 8 , wherein:
 a binding tape layer configured to finish the plurality of cores and the filling members so as to form a circular cross-section is provided; and   an armor bedding layer comprising a mixture of polypropylene yarns and bitumen is provided outside the binding tape layer.   
     
     
         11 . The marine cable according to  claim 10 , wherein:
 a metal armor layer is provided outside the armor bedding layer; and   an anticorrosion layer comprising a mixture of polypropylene yarns and bitumen is provided outside the metal armor layer.